What is the name of the irregular intrusion of igneous rock into another rock?

• A. Dike
• B. Sill
• C. Batholith
• D. Laccolith

Answer: (C)

A batholith is a very large, irregular intrusion of igneous rock. It forms when magma crystallizes underground over large areas, often integrating many smaller intrusions into one sprawling body that may later be exposed by erosion. This big, uneven volume contrasts with dikes, which are narrow sheets that cut across layers; sills, which run parallel to layers; and laccoliths, which are dome-shaped and push the overlying rocks upward. Because the term describes a substantial, irregular intrusion rather than a thin sheet or a dome, it is the best fit.